RE: switch blade cg
Start with it on the spar, you're almost always safe there.
FWIW, I had one of those and it was a horrible plane. The only way I could get it to balance without lead was to slap a Saito 91 on the nose. I fought thrust line issues with it enlessly until I scrapped it.
Godd luck with yours.
P.S. That thin fuse is VERY fragile.